Fred,
I never used any forumla. And like Roscoe, I have a 100 amp alternator which has been checked and puts out 102 amps on the test bench. They have a Yellow Top but I am not positive just what it is so far as difference goes. Mine is about 10" by 7" by 7" physically.
Looking in my Jegs book I see the yellow tops have more CCA, than the red tops do. Physical size is about the same but they don't say anything about how well they will take the vibration. The red top can be mounted upside down if you want and won't hurt it. The two yellow tops they show have 850 and 900 CCA. The Yellow tops state that they are deep cycle and that may be why they don't say anything about you can mount them in any position. Go in to one of your auto parts stores and look at both and see which would work for you.
Ron
